Mobile work machines are known from the prior art and serve, for example, to move loads or to perform mechanical work. It may be necessary in this respect to support the respective work machine for carrying out the work correspondingly on the ground. If this is done incorrectly, it can occur that the work machine topples over. In particular pole machines and cranes having long booms are particularly at risk in this respect. The error cause is in this respect often not only an exceeding of the permitted payload of the work machine, but rather a yielding of the subsurface long before the reaching of the maximum permitted payload of the work machine. There are currently no means of comparing the then current load carrying capacity of the ground with the ground pressure generated in the then current load state and thus of avoiding a yielding of the subsurface.
The estimation of the subsurface is difficult for the unit operator. The subsurface is typically determined beforehand by a geologist or by another expert, frequently while using various measurement devices.
It is therefore the object of the present invention to provide a work machine or a method in which the toppling over of the work machine is prevented due to a yielding subsurface.
This object is achieved by a method of operating a mobile work machine with a ground pressure limitation, comprising the steps: determining a maximum permitted ground pressure; calculating the actual ground pressure; comparing the calculated actual ground pressure with the maximum permitted ground pressure; and reporting the comparison result to the operator of the work machine and/or stopping a movement of the work machine that increases the ground pressure on an exceeding of a limit value of the actual ground pressure.
A ratio between the maximum tolerable ground pressure and the actually generated ground pressure can in this respect advantageously be made known to the operator at the then current unit position or work machine position. Not only a ground pressure can in this respect be delivered as operator information in the form of a number, but also or alternatively a color display having the colors green/yellow/red, with green indicating a permitted load, red indicating a non-permitted load, and yellow indicating a border load between a permitted load and a non-permitted load. A percentage-wise feedback is also conceivable in which the percentage of the maximum permitted ground pressure being reached is indicated.
In a further preferred embodiment, it is conceivable that a manual input is carried out by the operator and/or an automatic measurement of the maximum permitted ground pressure is carried out in the method of determining the maximum permitted ground pressure.
It is conceivable in a further preferred embodiment that a setting of the unit configuration of the work machine is carried out, in particular by the operator. The method in accordance with the invention can hereby advantageously be correspondingly adapted to a converted or modified work machine. A setting of the unit configuration can also take place automatically via corresponding sensors.
It is conceivable in a further preferred embodiment that a detection of the then current geometry of the work machine is carried out. The then current geometry can in this respect vary, for example, in that booms are extended or retracted or that supports are repositioned. If the geometry of the work machine varies during a work procedure in this respect, it is advantageously possible to react thereto in real time and to adapt the method correspondingly dynamically. The detection of the then current geometry of the work machine can in this respect also take place automatically, for example via corresponding sensors.
It is conceivable in a further preferred embodiment that a detection of the then current load of the work machine is carried out and/or that a calculation of the load of the work machine is carried out. A dynamic adaptation of the corresponding parameters within the method procedure can advantageously thus be carried out. If the load of the work machine or its strain changes, for example due to work movements of the work machine or changed wind conditions or similar factors, it is thus possible in accordance with the method to take this into account in the ground pressure limitation.
It is conceivable in a further preferred embodiment that the setting of the unit configuration of the work machine comprises the setting of a ballast and/or of a pole length and/or the setting of further components of the work machine.
The present invention also relates to a work machine, in particular to a pile driver and/or to a drill, having an apparatus for carrying out a method, comprising the steps: determining a maximum permitted ground pressure; calculating an actual ground pressure; comparing the calculated actual ground pressure with the maximum permitted ground pressure; and reporting the comparison result to an operator of the work machine and/or stopping a movement of the work machine that increases the ground pressure on an exceeding a limit value of the actual ground pressure.
It is conceivable in this respect in a particularly preferred embodiment that a sensor apparatus known, for example, from the prior art such as from DE 20 100 489 U1 is provided for an automatic measurement of the maximum permitted ground pressure.
Further details and advantages of the invention will be shown with reference to the Figures.